1. Field of Endeavor
The present invention relates to compact cryogenic-capable pressure vessels and more particularly to a threaded insert for compact cryogenic-capable pressure vessels.
2. State of Technology
Hydrogen has the potential to displace petroleum as a universal transportation fuel, reducing or eliminating petroleum dependence and associated tailpipe air pollutants and greenhouse gases. The predominant technical barrier limiting widespread use of hydrogen vehicles is sufficient onboard fuel storage capacity for highway vehicles within volume, weight, cost, and refueling time constraints.
There exist three technologies for automotive hydrogen storage: High pressure compressed gas storage, low-pressure absorption of hydrogen in porous and/or reactive materials, and storage as a cryogenic liquid. Each has significant fundamental drawbacks. Hydrogen stored as a compressed gas occupies a relatively large volume at ambient temperature. Materials which absorb hydrogen add significant weight, cost, and thermal complexity to onboard storage systems. Liquid hydrogen (LH2) storage has the potential for evaporative losses from distribution, transfer and refueling operations, in addition to pressure buildup due to heat transfer, which must be relieved by venting during periods of inactivity greater than several clays.
Over the past 10 years the Applicants have pioneered research and development of a more advantageous storage technology: cryogenic capable pressure vessels. This technology can store hydrogen more compactly than conventional ambient temperature pressure vessels, with lower weight than hydrogen absorption storage technologies, and with far greater thermal endurance than conventional low pressure LH2 storage, potentially eliminating evaporative losses under virtually all automotive usage conditions.
The subcomponents of such tanks must also be able to handle high pressure cryogenic conditions. However, most components are designed for only one specific subset such as low pressure cryogenic or high pressure and ambient temperatures and therefore cannot be used. Furthermore, conventional approaches to interface the tank with external components designed for high pressure cryogenic conditions take up a large amount of the system volume. Considering that storing enough hydrogen onboard a vehicle is key for customer acceptance, compact pressure vessel system designs will play an important role in enabling a transition to clean, practical, hydrogen vehicles.